Lavatories on commercial aircraft are typically vented to prevent undesirable odors from building up therein. Such odors may create an unpleasant environment aboard the aircraft, particularly on long flights. The lavatory vent may comprise a pipe or series of pipes which extend between the lavatory holding tank and the exterior of the aircraft. During flight at typical cruise altitudes, the pressure within the aircraft cabin and within the lavatory holding tank exceeds the pressure outside the aircraft, causing air to flow from the holding tank, through the vent pipes, and to the exterior of the aircraft. As the vented airstream exits the aircraft, it comes into contact with cold air surrounding the aircraft and rapidly cools. Moisture in the vented airstream condenses and forms ice which may adhere to the aircraft fuselage, flight control surfaces, or other external surfaces or components, potentially inhibiting operation of the aircraft. When the aircraft descends to warmer altitudes, the ice may break off and may damage the aircraft surfaces or components, and may also injure persons or property located on the ground below.
One method for reducing the moisture content of a vented airstream includes passing the airstream through a 90 degree bend in the vent pipe before the airstream exits the aircraft. One problem with this method is that a significant amount of moisture may remain in the airstream despite the 90 degree bend, causing ice to build up on the aircraft exterior and break off as discussed above. Another problem is that existing pipe networks may contain gaps which are deliberately formed therein to entrain air from outside the holding tank and thereby reduce the velocity of air vented from the holding tank. The gaps may allow moisture to leak from the pipes into the interior of the aircraft. Such moisture is undesirable because it may promote corrosion of the aircraft and may create slippery or otherwise hazardous working conditions within the aircraft.
Another method for reducing the moisture content of the vented airstream includes passing the air over a series of baffles. One problem with existing baffle devices is that they may not adequately drain the collected moisture into the holding tank. Another problem is that the existing devices may not provide for low velocity flow in the region of the baffles.